A single-dose GLP-1 autoinjector that will not start, click or empty: what the window shows, what to check, and who to call.
Key points
- 01A single-dose pen has no dose counter to read. Wegovy, Zepbound and the single-dose Mounjaro pen each deliver one fixed dose. There is nothing to dial and no counter returning to zero, so the checks that work on a multi-dose pen do not transfer. You read the inspection window instead.
- 02The lock has to be released and the base flat on skin. These devices are designed not to fire until the base is pressed flat against the skin with the lock turned off. A pen that does nothing when you press is very often a pen held at an angle or still locked. The instructions for use for your product show the exact order.
- 03Two clicks, and the window is the real confirmation. The published instructions describe a first click when delivery starts and a second when it ends, with a slow count as the fallback if you did not hear them. What confirms the dose is the grey plunger or fill indicator filling the inspection window, not the sound.
- 04Do not lift early and do not press again. Lifting the device before delivery finishes is the common cause of a partial dose. A pen that has fired cannot be reset or reused, and pressing it a second time is not a fix. Our guide on injecting a partial dose covers what comes next.
- 05A refrigerated pen empties slowly. Cold solution is more viscous and takes longer to leave the device, which reads as a pen that is stuck. The instructions for use describe letting a pen sit out to reach room temperature before injecting, which is a comfort question and a flow question at once.
- 06A device that never fired is a pharmacy call. If the window never changed and you used the pen the way the leaflet describes, set it aside, tape a note on it with the date, and call the dispensing pharmacy. Whether a dose was delivered is a prescriber question, not something to settle by injecting again.
Frequently asked questions
How do I know a single-dose pen actually delivered?+
By the inspection window rather than by sound. The instructions for use describe the grey plunger or fill indicator filling the window once delivery is complete. Educational information only, not medical advice.
Why does nothing happen when I press the pen?+
Most often the base is not flat against the skin or the lock has not been released. These devices are built to fire only when both conditions are met, so check the position and the lock before anything else.
Can I reuse a pen that did not fire?+
No. A single-dose device cannot be reset, and pressing it again is not a documented fix. Set it aside, label it with the date and call the pharmacy that dispensed it.
Does a cold pen matter?+
Yes, for flow and for comfort. Cold solution is thicker and takes longer to leave the device, which feels like a stuck pen. The leaflet describes letting the pen reach room temperature first.